Corrosion-resisting and wear-resisting alloy and device using the same

ABSTRACT

To provide a corrosion-resisting and wear resisting alloy including cobalt, nickel or iron as a base used for a sliding part or a valve seat for a machine, and restraining erosion and corrosion caused by eutectic carbide constituting the alloy in an atmosphere with dissolved oxygen.  
     A material is selected from a cobalt base added with Cr and/or W, a nickel base added with Fe and/or Cr, and an iron vase added with Cr and/or Ni. The material is cast into an ingot or a slab to produce an intermediate material. The intermediate material comprises mesh-like eutectic carbide and a base material surrounded by the eutectic carbide. A heat plastic forming is applied to the intermediate material at a temperature 650° C. or more and the solidus temperature or less. The eutectic carbide is formed into multiple grains or clusters as a discontinuous distribution. A resulting corrosion-resisting and wear-resisting alloy has 0.1 to 0.5 of coefficient of friction, and 300 to 600 Hv of Vickers hardness without age-hardening process.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a corrosion-resisting andwear-resisting alloy, and a fluid device and a dynamic device using thealloy.

[0003] 2. Description of the Prior Art

[0004] A valve seat or a sliding part, where a corrosion-resisting andwear-resisting alloy which includes cobalt as a base, which is excellentin corrosion-resisting and wear-resisting capabilities, and has a highdegree of hardness, and is added with Cr and/or W, is overlaid toprevent an erosion damage on a valve seat during operation or a gallingwhile a valve is in motion is used for valves such as a safety valve ina plant facility such as a turbine power generating facility.

[0005] In late years, hydrogen peroxide solution and the like isintroduced to adjust water quality in a plant facility such as a turbinepower generating facility. As the result, the amount of dissolved oxygenincreases on the down stream of the introduction point, and an erosiondamage is generated on eutectic carbide of the corrosion-resisting andwear-resisting alloy, which includes cobalt as a base, is added with Crand/or W, comprises the eutectic carbide and the base material of a caststructure, and is overlaid on a seat surface of a valve and a slidingface to prevent erosion and a galling.

[0006] It is also reported that the base material of the cast structureis detached, thereby generating corrosion after the erosion damage ofthe eutectic carbide when a flow (such as water flow) is present.

[0007] The reports relevant to the earlier report include “Thermal andNuclear Power Vol. 30-5 Processing Method for Boiler Water with Oxygenand Ammonia in a Steam System in a Thermal Power Plant”, “Damage onMachinery 1982 2 VEW Operation Experience in a Combined Operation Methodat Gerstein Power Generating Plant”, and “Materials and Environment Vol.47, No.3, Effect of Heat Treatment Condition on Grain Boundary Erosionat Welded Part of Cobalt-Base Alloy”.

[0008] Those reports conclude that there is no effective mean toeliminate a generation of the erosion, and it has been a problem.

[0009] On the other hand, an expansion valve preventing a generation oferosion at a valve port provided with an orifice by integrating anorifice member made of a metal material with higher degree of hardness(150 to 500 in Vickers hardness) than that of a valve body with thevalve body is disclosed in Japanese application patent laid-openpublication No. Hei 08-334280 (corresponding to U.S. Pat. No. 6164624Specification).

[0010] An increased wear-resisting capability of a blade by attaching abar-like wear-resisting material including cobalt, nickel, tungsten,manganese, and selenium to a rear edge of the steam turbine blade withfriction surfacing is disclosed in Japanese application patent laid-openpublication No. Hei 05-208325 (corresponding U.S. Pat. No. 5183390Specification). It is disclosed that a caution should be paid to avoidthe bar-like wear-resisting material from presenting melting in terms ofpreventing a change in the degree of hardness and a crack due toshrinkage when the wear-resisting material is attached to the blade byfriction surfacing,

[0011] A valve where a valve seat comprising 30 to 45 weight % of Cr,3.0 to 8.0 weight % of Ti, 0 to 10 weight % of Mo, and the balance Niis-diffusion-bonded to a valve element and a valve casing is disclosedin Japanese application patent laid-open publication No. Sho 59-179283.

[0012] A valve where a valve seat comprising 10 to 45 weight % of Cr,1.5 to 6 weight % of at least either of Al or Ti, and 20 weight % orless of Mo, and the balance Ni is diffusion-bonded to a valve elementand/or a valve casing is disclosed in Japanese application patentlaid-open publication No. Sho 60-86239.

[0013] A valve where a valve seat comprising a cemented carbide materialor a heat-resisting material is brazed through an amorphous alloy layerto a valve seat part of a valve casing is disclosed in Japaneseapplication patent laid-open publication No. Hei 4-19476.

[0014] A technique where material of high carbon martensitic stainlesssteel is made into an intermediate material with an intermediatedimension with hot plastic forming, the intermediate material is appliedwith cold plastic forming, and the intermediate material is applied withthe hot plastic forming again at 850° C. to obtain a steel material withan intended dimension is disclosed in Japanese application patentlaid-open publication No. Hei 7-16610. The average dimension of theeutectic carbide in the steel material with the intended dimensionreaches 4.2 micrometer with the disclosed technique in the publication.

[0015] Valves including safety valves used for a turbine powergenerating plant have a high flow speed at a valve seat duringoperation. Cobalt has a high degree of hardness, and is excellent incorrosion-resisting and wear-resisting capabilities. A valve seat whichis made of a corrosion-resisting and wear-resisting alloy includingcobalt as a base added with Cr and/or W is used for these valves.

[0016] A valve casing where the corrosion-resisting and wear-resistingalloy is used on a guide face for guiding a valve element, and on aninner face of a cage to prevent a galling while a vale is in operation,is used for a cage valve.

[0017] However, when the aforementioned valve seat made of thecorrosion-resisting and wear-resisting alloy is used in a hightemperature/high pressure water/steam atmosphere with high dissolvedoxygen, a base material layer of a cast structure and eutectic carbidesurrounding the base material layer of the cast structure as a meshshape in the alloy are selectively corroded by the dissolved oxygen inthe fluid. This makes the surface of the valve seat rougher, theeutectic carbide is corroded and detached with an additional effect of atunnel effect (F. j. Heymann: Machine Design. 42, 118 (1970)), which iscaused by a penetration of a high speed jet into a corroded and damagedpart, the base material of the cast structure which lost the supportfrom the mesh-like eutectic carbide is easily detached by the flow,resulting in a generation of an erosion in the corrosion-resisting andwear-resisting alloy.

SUMMARY OF THE INVENTION

[0018] The purpose of the present invention is to provide acorrosion-resisting and wear-resisting alloy with increasedcorrosion-resisting and erosion-resisting capabilities by restrainingcontinuing corrosion of eutectic carbide in the corrosion-resisting andwear-resisting alloy in an atmosphere with dissolved oxygen.

[0019] The purpose of the present invention is also to provide deviceswhere the corrosion-resisting and wear-resisting alloy with increasedwear-resisting and corrosion-resisting capabilities is used atwear-resisting parts and erosion-shield parts.

[0020] The principal part of the present invention to attain the purposeis described below.

[0021] A corrosion-resisting and wear-resisting alloy is obtained byselecting a material from cobalt base added with Cr and/or W, nickelbase added with Fe and/or Cr, and iron base added with Cr and/or Ni,casting the material into an ingot or a slab as an intermediatematerial, applying hot plastic forming at a temperature which is 650° C.or more and the solidus temperature or less to the intermediatematerial, which includes a structure comprising mesh-like eutecticcarbide and a base material surrounded by it, forming the eutecticcarbide as a discontinuous distribution in a form of multiple grains orclusters. The coefficient of friction of the corrosion-resisting andwear-resisting alloy is 0.1 to 0.5, and the Vickers hardness without agehardening process of it is 300 to 600 Hv.

[0022] The cobalt base added with Cr and/or W comprises 0.1 to 3.5% ofC, 25% or less of Ni, 25 to 35% of Cr, 5% or less of Fe, 20% or less ofW, 1.5% or less of Mn, and 1.5% or less of Si in weight ratio, thebalance Co and inevitable impurities. The nickel base added with Feand/or Cr comprises 0.1 to 2.5% of C, 3 to 9% of Si, 7 to 25% of Cr, 0.5to 5% of B, 2 to 6% of Fe, 1 to 5% of W, and 17% or less of Mo in weightratio, the balance Ni and inevitable impurities. The iron base addedwith Cr and/or Ni comprises 0.1 to 1.5% of C, 0.3 to 4% of Si, 4 to 9%of Ni, 3% or less of Mo, 6 to 10% of Mn, and 15 to 25% of Cr in weightratio, the balance Fe and inevitable impurities.

[0023] For example, cobalt base added with Cr and/or W is cast into anintermediate material typified by an ingot or a slab. This cast materialcomprises a base material and eutectic carbide of a cast structure. Ahot plastic forming is applied to the eutectic carbide, which has a highdegree of hardness and low ductility, and is fragile and distributedcontinuously as a mesh. The intermediate material becomes fine grains orclusters. The structure of the base material penetrates into gapsgenerated in the eutectic carbide. The base material with a low degreeof hardness, high ductility, and strength is distributed around thegrain-like or cluster-like eutectic carbide, thereby making the eutecticcarbide discontinuous.

[0024] Simultaneously, the diffusion of large amount of chrome existingin the eutectic carbide is accelerated by maintaining it at 650° C. ormore, thereby reducing chrome-deficiency layers around the eutecticcarbide, resulting in a corrosion-resisting and wear-resisting alloysimultaneously having an increased corrosion-resisting capability of theeutectic carbide.

[0025] With this, eutectic carbide, which is distributed as mesh, and isin a cast structure which is made by dissolving cobalt as a base alongwith Cr and/or W and comprises the base material and the eutecticcarbide, is made into multiple clusters and grains as discontinuedeutectic carbide, thereby making an erosion phenomenon discontinued,very shallow and partial.

[0026] As the result, the progress of the erosion is restrained, and atunnel effect (F. j. Heymann: Machine Design. 42, 118 (1970)), which iscaused by a penetration of a high speed jet into a corroded and damagedpart is restrained, thereby increasing the erosion/corrosion-resistingcapability.

[0027] The effect described above increases the erosion-resisting andcorrosion-resisting capabilities.

[0028] Also, the diffusion of large amount of chrome existing in theeutectic carbide into the periphery of the eutectic carbide isaccelerated by maintaining it at 650° C. or more, thereby reducingchrome-deficiency layers around the eutectic carbide containing Cr,resulting in a corrosion-resisting and wear-resisting alloysimultaneously having an increased corrosion-resisting capability of theeutectic carbide.

[0029] For a nickel base material added with Fe and/or Cr, or an ironbase material added with Cr and/or Ni, a corrosion-resisting andwear-resisting material is obtained in the same way, thereby increasingerosion/corrosion-resisting capability.

[0030] When the corrosion-resisting and wear-resisting alloy ispartially or entirely melted, the eutectic carbide at the melted partforms mesh-like eutectic carbide with a low corrosion-resistingcapability. Thus, the corrosion-resisting and wear-resisting alloy ismachined into an arbitrary shape, and is used after it is joined withoutmelting to a base metal, which is a base to which thecorrosion-resisting and wear-resisting alloy is attached.

[0031] Since the mesh-like eutectic carbide does not exist, and is madeinto clusters or grains, a fluid machine using the alloy such as a pump,a valve, a pressure device, and a turbine presents highcorrosion/erosion-resisting capabilities under a corrosive atmosphere.

[0032] A dynamic machine such as a pump, a valve, a turbine, and anengine where the corrosion-resisting and wear-resisting alloy withoutchanting the metal composition is joined to a base metal and used for asliding part or a contact part, presents highcorrosion/erosion-resisting capability under a corrosive atmosphere.

[0033] The obtained coefficient of friction can be 0.1 to 0.3, which isas low as diamond (coefficient of friction of 0.1 when no lubricant),sapphire (coefficient of friction of 0.2 when no lubricant), and ruby,thereby reducing friction resistance compared with 0.35 to 0.8 of othermetals such as brass (coefficient of friction of 0.35 when no lubricant)and steel (coefficient of friction of 0.8 when no lubricant).

[0034] The corrosion-resisting and wear-resisting alloy is used for awear-resisting part or an erosion shield for a fluid machine, and asliding part or a contact part for a dynamic machine.

[0035] When the corrosion-resisting and wear-resisting alloy of thepresent invention is attached to a fluid machine or a dynamic machine,it is attached to the wear-resisting part and the erosion shield part,and the sliding part and the contact part while maintaining thecomposition of the corrosion-resisting and wear-resisting alloy as muchas possible. As the attaching method, a joining method which does notmelt the corrosion-resisting and wear-resisting alloy is employed. As anexample of the joining method, liquid phase diffusion welding isavailable.

[0036] More specifically, the corrosion-resisting and wear-resistingalloy of the present invention is applied to a valve seat attached tocontact faces of a valve element and a valve casing provided on a pipingsystem in an atomic power generating plant and the like, a contact facematerial for at least either of contact faces of a seat or a washerrotating relatively to each other about a rotating shaft of a pump,valve seats attached to contact faces of a valve seat part and a valveprovided on a cylinder head of an internal combustion engine, and acontact face material for at least either of contact faces of a valvelifter and a cam of an internal combustion engine.

[0037] The present invention reduces the degradation of entirecorrosion-resisting and wear-resisting capabilities caused by corrosionand damage to eutectic carbide in a corrosion-resisting andwear-resisting alloy.

[0038] Applying the corrosion-resisting and wear-resisting alloy of thepresent invention to sliding parts and contact parts of differentdevices reduces roughness on the sliding parts and the contact parts ofthe devices caused by the corrosion and the damage of the eutecticcarbide under a corrosive environment, thereby maintaining properfriction resistance on the sliding parts and the contact parts. As theresult, the present invention provides devices including sliding facesand contact faces with low friction.

[0039] A rotating device, which is an embodiment of the presentinvention, includes a mechanical seal device sealing between a rotatingshaft and a casing. The mechanical seal device comprises a first seal,which rotates with the rotating shaft, and a second seal, which isinstalled on the casing, and is in contact with the first seal. At leasteither the first seal or the second seal is a corrosion-resisting andwear-resisting part where grain-like or cluster-like eutectic carbide isdiffused in the matrix part of the metal micro structure, and includesthe corrosion-resisting and wear-resisting alloy part which comes incontact with the other seal part, and a main body. Thecorrosion-resisting and wear-resisting alloy part is diffusion-welded tothe main body. Since the seal part includes the corrosion-resisting andwear-resisting alloy part, which is diffusion-welded to the main body,the corrosion-resisting and wear-resisting alloy part, which isdiffusion-welded, includes grain-like or cluster-like eutectic carbideas described before, not mesh-like eutectic carbide. Seizure, wear, andacceleration of corrosion of the seal member caused by an increase ofthe temperature at the seal due to heat generated at the contact part ofthe first and the second seals is restrained, thereby increasing thecorrosion-resisting and wear-resisting capabilities at the seal,decreasing the frequency of maintenance for the mechanical seal deviceincluding the first and second seals, and increasing the life of themechanical seal device. This leads to relieving the maintenanceoperation for the rotating device. Since the corrosion-resisting andwear-resisting alloy has a small coefficient of friction, the heatenergy generated at the contact part of the first seal and the secondseal decreases. This leads to a reduction of the power rotating therotating shaft of the rotating device.

BRIEF DESCRIPTION OF THE DRAWINGS

[0040]FIG. 1 is an SEM photograph indicating a metal structure of asurface of a corrosion-resisting and wear-resisting alloy includingcobalt as a base added with Cr and/or W (a), and its schematic (b).

[0041]FIG. 2 is an enlarged part (a) of the metal structure of thecorrosion-resisting and wear-resisting alloy from FIG. 1, and itsschematic (b).

[0042]FIG. 3 is a metal structure indicated by a face analysis of asurface of a corrosion-resisting and wear-resisting alloy includingcobalt as a base added with Cr and/or W (a), and its schematic (b).

[0043]FIG. 4 is a metal structure of a surface of a corrosion-resistingand wear-resisting alloy including cobalt as a base added with Cr and/orW after heat plastic forming (a), and its schematic (b).

[0044]FIG. 5 is a metal structure indicated by a face analysis of asurface of a corrosion-resisting and wear-resisting alloy includingcobalt as a base added with Cr and/or W after heat plastic forming (a),and its schematic (b).

[0045]FIG. 6 is a schematic of a repeated progress of a damage caused bydissolved oxygen on a corrosion-resisting and wear-resisting alloyincluding cobalt as a base added with Cr and/or W.

[0046]FIG. 7 is a schematic of a restraining status of a damage causedby dissolved oxygen on a corrosion-resisting and wear-resisting alloyincluding cobalt as a base added with Cr and/or W after heat plasticforming.

[0047]FIG. 8 is a SEM photograph indicating a metal structure obtainedby a Strauss test applied to a corrosion-resisting and wear-resistingalloy including cobalt as a base added with Cr and/or W after heatplastic forming.

[0048]FIG. 9 is a chart indicating a coefficient of friction obtained bya sliding test applied to a corrosion-resisting and wear-resisting alloyincluding cobalt as a base added with Cr and/or W after heat plasticforming.

[0049]FIG. 10 is a piping system diagram of a nuclear power generatingplant.

[0050]FIG. 11 is a lengthwise section view of a gate valve adopted forthe piping system of the nuclear power generating plant

[0051]FIG. 12 is a section view indicating contact states between avalve element and individual valve seats, and between a valve casing andthe individual valve seats for the gate valve in FIG. 11.

[0052]FIG. 13 is an entire view of an internal combustion engine with apartial section view.

[0053]FIG. 14 is an enlarged section view around a valve indicated inFIG. 13.

[0054]FIG. 15 is an enlarged section view of a contact part between thevalve and a seat in FIG. 14.

[0055]FIG. 16 is a section view of a pump.

[0056]FIG. 17 is a section view of a neighborhood of a mechanical sealof a pump in FIG. 16.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0057] A typical SEM photograph of a surface of a corrosion-resistingand wear-resisting alloy including cobalt as a base added with Cr and/orW is shown in FIG. 1 (Note that (a) is an SEM photograph, (b) is theschematic of (a). Same arrangement is repeated in FIGS. 2 to 5). An SEMphotograph with a high magnitude is shown in FIG. 2. An SEM photographfor Cr face analysis taken at the same position on the face of thecorrosion-resisting and wear-resisting alloy as in FIG. 2 is shown inFIG. 3.

[0058] An SEM image of a metal structure of a face of thecorrosion-resisting and wear-resisting alloy after hot plastic formingsuch as forging and rolling is shown in FIG. 4. An SEM photograph for Crface analysis taken at the same position on the face of thecorrosion-resisting and wear-resisting alloy as in FIG. 4 is shown inFIG. 5.

[0059] Eutectic carbide 1 with principal components of Cr and C in FIGS.1, 2, and 3 is continuously distributed as a mesh in a base material 2of a cast structure including cobalt as a principal component on asurface of the surface-melted alloy.

[0060] An embodiment of the present invention is shown in FIGS. 4 and 5.The eutectic carbide 1 is distributed as grains or clusters with respectto the base material 2 uniformly but discontinuously on a surface of thecorrosion-resisting and wear-resisting alloy. The eutectic carbide 1changes from mesh to grains or clusters, thereby reducing the ratio ofthe eutectic carbide occupying the surface.

[0061]FIG. 6 is a schematic showing a progress of repeated damage to thecorrosion-resisting and wear-resisting alloy including cobalt as a baseadded with Cr and/or W due to dissolved oxygen.

[0062] As the corrosion/erosion on the corrosion-resisting andwear-resisting alloy progresses, the base layer 2 of the cast structuretends to detach because the dissolved oxygen corrodes the eutecticcarbide 1.

[0063] As indicated in the SEA photograph in FIG. 3, the eutecticcarbide 1 continuous as a mesh exists in the conventionalcorrosion-resisting and wear-resisting alloy including cobalt as a baseadded with Cr and/or W. The corrosion of the eutectic carbide 1 and thedetaching of the base layer 2 of the cast structure due to the dissolvedoxygen occur continuously, resulting in a progress of thecorrosion/erosion under an atmosphere of dissolved oxygen.

[0064] On the other hand, in the corrosion-resisting and wear-resistingalloy which includes cobalt as a base added with Cr and/or W, and isapplied with hot plastic forming, the eutectic carbide 1 existsdiscontinuously as grains or clusters, the corrosive damage to theeutectic carbide 1 due to the dissolved oxygen is limited to theeutectic carbide 1 on a face facing to the dissolved oxygen.

[0065] After the eutectic carbide 1 on the surface is corroded anddetached, the corrosive damage does not progress any further. This isdescribed using a schematic in FIG. 7 showing a restrained damage due tothe dissolved oxygen.

[0066] To verify the effect described before, JIS G 0575 “Sulfuricacid/cupric sulphate corrosion test on stainless steel” (Strauss test)is applied. According to a test conducted by Takahisa and Honda where asimilar test was applied to a corrosion-resisting and wear-resistingalloy of cobalt base including a mesh-like continuous distribution ofeutectic carbide (Materials and Environment Vol. 47, No.3, Effect ofHeat Treatment condition on Grain Boundary Erosion at Welded Part ofCobalt-Base Alloy), it is reported that a progress of a corrosion isobserved at surface-melted alloy of the corrosion-resisting andwear-resisting alloy of cobalt base.

[0067] The similar test is applied to the corrosion-resisting andwear-resisting alloy of cobalt base added with Cr and/or W after aplastic forming such as forging and rolling, little etching was observedon the surface, no progress of a corrosion is present into the depthdirection, and an excellent corrosion-resisting capability is confirmed.The test result is presented in FIG. 8 and Table 1. FIG. 9 shows ameasuring result of the coefficient of friction with respect to theincrease/decrease of the number of sliding. TABLE 1 Strauss test:Corrosion depth in Co-base alloy (mm) Co-base alloy with Co-base alloywith eutectic eutectic carbide with carbide with discontinuouscontinuous mesh-like grain- or cluster-like Material distributiondistribution Pre-heating 600° C. 600° C. 700° C. temperature Testing0.51 to 0.62 mm As slight as No damage period etching 16 hours(impossible to measure) Testing 3 mm or more Up to 0.1 mm As slight asperiod etching 150 hours (impossible to measure)

[0068] The corrosion depth under a corrosive environment for thecorrosion-resisting and wear-resisting alloy of cobalt base added withCr and/or W, where the eutectic carbide 1 is distributed discontinuouslyas grains or clusters, the corrosion depth is restrained to about{fraction (1/30)} of that of conventional alloys, and the corrosiondepth is restrained further by increasing a pre-heating temperature todiffuse Cr further.

[0069] As the result, the corrosion-resisting and wear-resisting alloywith the eutectic carbide 1 distributed discontinuously as grains orclusters restrains the corrosion due to the dissolved oxygen, resultingin restraining the erosion.

[0070] When the cases where pre-heating temperature of thecorrosion-resisting and wear-resisting alloy of cobalt base added withCr and/or W is about 600° C. and is 700° C. are compared, thecorrosion-resisting capability of the grain-like or cluster-likeeutectic carbide 1 presents higher corrosion-resisting capability in thecase for 700° C., where Cr diffuses more, and joining the alloy with thebase material at a higher pre-heating temperature provides bettercorrosion-resisting and wear-resisting capabilities.

[0071] For a corrosion-resisting and wear-resisting alloy of nickel baseadded with Fe and/or Cr, and a corrosion-resisting and wear-resistingalloy of iron base added with Cr and/or Ni, conducting heat plasticforming in a state heated, up to the solidus temperature or lessincreases the corrosion-resisting and wear-resisting capabilities as forthe corrosion-resisting and wear-resisting alloy of cobalt base addedwith Cr and/or W, simultaneously providing a sliding surface with a lowfriction.

[0072] For a corrosion-resisting and wear-resisting alloy of iron baseadded with Cr and/or Ni, conducting heat plastic forming in a stateheated up to the solidus temperature or less increases thecorrosion-resisting and wear-resisting capabilities as for thecorrosion-resisting and wear-resisting alloy of cobalt base added withCr and/or W, simultaneously providing a sliding surface with a lowfriction.

[0073] The material components of the corrosion-resisting andwear-resisting alloy of cobalt base added with Cr and/or W comprises 0.1to 3.5% of C, 25% or less of Ni, 25 to 35% of Cr, 5% or less of Fe, 20%or less of W, 1.5% or less of Mo, and 1.5% or less of Si in weightratio, the balance Co and inevitable impurities.

[0074] The material components of the corrosion-resisting andwear-resisting alloy of nickel base added with Fe and/or Cr comprises0.1 to 2.5% of C, 3 to 9% of Si, 7 to 25% of Cr, 0.5 to 5% of B, 2 to 6%of Fe, 1 to 5% of W, and 17% or less of Mo in weight ratio, the balanceNi and inevitable impurities.

[0075] The material components of the corrosion-resisting andwear-resisting alloy of iron base added with Cr and/or Ni comprises 0.1to 1.5% of C, 0.3 to 4% of Si, 4 to 9% of Ni, 3% or less of Mo, 6 to 10%of Mn, and 15 to 25% of Cr in weight ratio, the balance Fe andinevitable impurities.

[0076] Applying a hot plastic forming to these corrosion-resisting andwear-resisting alloys increases the corrosion-resisting andwear-resisting capabilities, simultaneously providing acorrosion-resisting and wear-resisting sliding surface with a lowfriction.

[0077] The average coefficient of friction obtained by measuringfriction of a face of the corrosion-resisting and wear-resisting alloyis 0.16 without lubrication in a room atmosphere, and is 0.19 in asaturated steam atmosphere at 288° C. The metal components of thecorrosion-resisting and wear-resisting alloy used for the frictionmeasuring are described in Table 2, and the eutectic carbide in thecorrosion-resisting and wear-resisting alloy takes a form ofdiscontinuous distribution of multiple grains or clusters. TABLE 2Composi- tion Ni Fe Mo C Si Cr Co W Weight % 2.59 2.67 0.07 1.03 0.5929.73 Balance 3.86

[0078] The corrosion-resisting and wear-resisting alloy of the presentinvention is used for different devices as described below. FIG. 10presents a piping system for a nuclear power generating plant. A largenumber of gate valves and check valves are installed on a watersupplying pipe 11 of the piping system 10. Since the gate valves andcheck valves installed on the water supplying pipe 11 are smaller than awater-supplying pump 12, individual supplied water heaters 13, 14, andother devices installed in the course of the water supplying pipe 11,and the number of the gate valves and check valves is very large, thegraphical representation of the gate valves and the check valves aresuppressed.

[0079] In the nuclear power generating plant, high temperature and highpressure steam obtained inside a nuclear reactor pressure vessel 16 isintroduced into a high pressure turbine 18 through a main steam piping15. Then the steam exhausted from the high pressure turbine 18 isintroduced to a low pressure turbine 19. The rotating forces of theseturbines drive a generator 20. The steam which has passed through thehigh pressure turbine 18 and the low pressure turbine 19 is exhaustedfrom the high pressure turbine 18 and the low pressure turbine 19, andis condensed into water in a main condenser 22 and a gland steamcondenser 21. The water is returned to the nuclear reactor pressurevessel 16 through the water supplying system 10 including the gatevalves and the check valves in addition to the water supplying pump 12,the individual supplied water heaters 13, 14, and the water supplyingpipe 11.

[0080] The following section describes an example where the presentinvention is applied to a gate valve among the valves adopted for thepiping of a water supplying system 46.

[0081] The FIG. 11 shows a lengthwise section of the gate valveinstalled on the water supplying pipe 11 of the water supplying system10. As in FIG. 12, a ring-like plate 31 made of a cobalt-base alloy ismounted as a valve seat on a valve element 30 side of the gate valve.The ring-like plate 31 made of the cobalt-base alloy is also installedon a slide face of a valve seat 33 of a valve casing 32 side.

[0082] The cobalt-base alloy includes 1.0 weight % of C, 30.0 weight %of Cr, and 3.9 weight % of W. Eutectic carbide in the cobalt-base alloyis made into clusters or grains less than 30 micrometer by heat forgingor heat rolling the cobalt-base alloy. The cobalt-base alloy plate 31 isjoined to the valve seat 33 of the valve casing 32 and a valve seat partof the valve element 30 with liquid phase diffusion welding as indicatedin FIG. 12.

[0083] The valve element 30 of the gate valve takes a disk-like shape,which is thick at the top and thin at the bottom, and is drivenupward/downward in association with the upward/downward motion of avalve stem, thereby opening/closing a flow of water or steam flowinginto the valve casing 32 in the left/right direction in the Figure.

[0084] The following section describes a specific example for installinga ring-like plate made of the cobalt-base alloy 31 to the valve element30. Protrusions 34 protruding toward left and right is provided byproviding steps on the left and the right surfaces of the valve element30 of the gate valve. An insert material for joining is placed inrecessed part which is generated by providing the steps. The ring-likeplate 31 with thick ness of about 7 mm is placed on the surface of theinsert material for joining such that the plate 31 is engaged with theprotrusions 34. Only the insert material for joining is melted to attachthe ring-like plate 31 to the valve element 30 with liquid phasediffusion welding.

[0085] The insert material used for the liquid phase diffusion weldingis an Ni-base alloy including 4.5 weight % of Si and 3 weight % of B,and is fully melted at about 1040° C. or more. The condition for theliquid phase diffusion welding is 1100° C. for the joining temperature,1 hour for the maintained period, 1 to 2 mult 10⁻⁴ Torr for the degreeof vacuum, and 15 g/cm² for the applied pressure. For the cooling afterthe joining, about 150° C./h is from 1000° C. to 650° C., about 100°C./h is from 650° C. to 425° C., and natural cooling with air cooling inroom is from 425° C.

[0086] A ring-like protrusion 35 is also machined on the valve seat 33.An insert material for joining is placed in a recessed part around theprotrusion. The ring-like plate 31 with thick ness of about 7 mm isplaced on the surface of the insert material for joining to engage withthe protrusion 35. Only the insert material for joining is melted toattach the ring-like plate 31 to a valve seat 7 with liquid phasediffusion welding. The ring-like plate 31 , the material for joining,the conditions for the liquid phase diffusion welding, and the coolingcondition are the same as those for the joining of the valve element 30to the plate 31.

[0087] The valve element 30, the plate 31 and the valve seat 33 do notmelt at the joining temperature of 1100° C. Material of a part of thevalve element 30 and the valve seat 33 where the plates 31 are installedis S25C, carbon steel for machine structure. The thermal expansioncoefficient of the carbon steel for machine structure S25C is smallerthan that of the Co-base alloy. The ring-like protrusions 34, 35 (steps)with the height of 2 mm are provided to internally come in contact witha ring-like plates 6 to be joined on the surfaces of the valve element30 and the valve seat 33 opposing to each other as described in FIG. 12.This facilitates positioning the plates 31 to the valve element 30 andthe valve seat 33 during the joining, and simultaneously increasing aresistance against a searing force added to a sliding part and thejoined part when the gate vale is in operation.

[0088] Both of the plates 31 which serve as a valve seat on the valveelement 30 side appear as a ring seen from the left and the right of thepage respectively in FIG. 12. The ring-like plates 31 are joined suchthat they are in contact with the outer periphery of the circularprotrusion 34 on the left and right sides of the valve element 30.

[0089] The valve seat 33 on the side of the valve casing 32 iscylindrical, and a valve set 33 is integrated into the valve casing 32.An end face on the side of the valve element 30 of the valve seat 33 isa sliding face. The end face is structured such that the ring like plate31 is in contact with and is liquid-phase-diffusion welded to the outerperiphery of the ring-like protrusion 35. Both of the protrusions 34, 35are 2 mm in height, which is smaller than 7 mm of the thickness of thering-like plates 31.

[0090] For the gate valve manufactured with this method, the mutualcontact faces of the valve element and the valve casing are structuredwith the plates 31. Since the eutectic carbide in the Co-base alloy,which is the material for the plate 31, is distributed discontinuouslyas multiple grains or clusters after the liquid phase diffusion welding,the phenomenon that an atmosphere generating a corrosive environmentsuch as dissolved oxygen corrodes the eutectic carbide continuously isrestrained. This restrains the detach of matrix of the cast structure ofthe Co-base alloy, thereby restraining the progress of the corrosion anderosion of the valve seat, resulting in preventing the deterioration ofthe leakage-resisting capability of the gate valve.

[0091] For this embodiment, the Co-base alloy plates 31 are used as thering-like corrosion-resisting and wear-resisting alloy. As describedbefore, the corrosion-resisting and wear-resisting alloy of nickel baseadded with Fe and/or Cr, the corrosion-resisting and wear-resistingalloy of iron base added with Cr and/or Ni, and the Ni-base alloy andthe Fe-base alloy, where the alloy including components described beforein the Table 2 is applied with heat forging or heat rolling to make theeutectic carbide in the alloy distribute discontinuously are used aswell.

[0092] Though in this embodiment, Ni-base alloy with a low melting pointis used as an insert material, an Fe-base or Co-base insert with a lowmelting point is used as well. The same constitution as in theembodiment of the present invention can be applied to a sliding part anda contact part of a valve seat and the like in a check valve, a safetyvalve, and a globe valve in addition to a gate valve to provide aneffect on restraining the decrease of the leakage-resisting capability,the controllability and the operation capability of the individualvalves.

[0093] This embodiment has an effect of maintaining the normal functionof a valve used for an atomic power generating plant for a long period,thereby increasing the reliability of the atomic power generating plantwith the effect.

[0094] In a plant including a piping system integrated with the valvedescribed in this embodiment, corrosion and erosion of sliding partssuch as a valve seat due to dissolved oxygen are restrained whenhydrogen peroxide solution is infused in the piping for the purpose ofadjusting water quality, thereby providing an effect on the increase ofthe safety of the plant.

[0095] Especially, when the valve of the present embodiment is installedand used on a water supplying system of a nuclear power generatingplant, corrosion and detaching of the eutectic carbide of the Co-basealloy applied to the valve seat, and effusion and diffusion of cobaltinto the water supplying system after the corrosion and the detachingare restrained. As the result, the effusion and diffusion of the cobaltand the activation of the cobalt are restrained, thereby remarkablyreducing exposure to radiation of workers in the nuclear powergenerating plant.

[0096] The corrosion-resisting and wear-resisting alloy of the presentinvention is applied to an internal combustion engine as follows. Aninternal combustion engine using gasoline as fuel is provided with acylinder 40 for combusting gasoline as described in FIGS. 13, 14, and15. The cylinder 40 is closed by a cylinder head 41 at the top. Thecylinder head 41 is provided with an intake port and an exhaust port,and the individual intake port and exhaust port are opened/closed byvalves 42.

[0097] The valves 42 are operated to open/close by a valve systemprovided on the cylinder head 41. The valve system comprises a spring 43provided around a driving shaft of the valve 42, a valve lifter 44connected at the top end of the driving shaft, an adjusting shim 45provided at the top of the valve lifter 44, a cam 46 which is in contactwith the top face of the adjusting shim 45, and a power transmittingmean which drives rotatingly the cam 46 using the output of the engine.

[0098] A part of the output of the engine is used to rotate the cam 46in the valve system. The motion of the cam 46 pushes down the valvelifter 44 through the adjusting shim 45 resisting against the spring 43.The pushing down motion departs the valves 42 downward from valve seats47 of the individual intake ports and exhaust ports, thereby opening theintake port and the exhaust port where the valves 42 are installed.

[0099] As the cam 46 rotates further, the valves 42 come in contact withthe valve seats 47 to close the valves 42. The contact parts between thevalve seats 47 and valves 42 serve as a seal to prevent the gas insidethe cylinder 40 from leaking.

[0100] The valve system including this motion presents friction due to asliding motion between the adjusting shim 45 and the cam 46. Frictionalso presents between the valve 42 and the valve seat 47. Driving thevalve system resisting against these frictions generate a loss in theoutput of the engine, thereby reducing the engine efficiency.

[0101] A Co-base alloy 48 as a corrosion-resisting and wear-resistingalloy is joined to the contact parts between the valve 42 and the valveseat 47 in the engine with a liquid phase diffusing welding 49 asindicated in FIGS. 14 and 15. This joining method is conducted as theliquid phase diffusion welding described before, and the same coolingcondition is applied. The Co-base alloy 48 is at least heat forgedbefore hand, and is made into a metal structure where the eutecticcarbide are composed into multiple grains or clusters in the basematerial of the cobalt.

[0102] The Co-base alloy including the eutectic carbide composed asmultiple grains or clusters in the base material is joined with theliquid phase diffusion welding to the top end of the valve lifter 45 toform the adjusting shim 4.

[0103] The compositions of the Co-base alloy 48 and the insert materialused for the liquid phase diffusion welding is indicated in Table 3.TABLE 3 (Weight %) Co Cr W C Fe Ni Other Co-base Bal 29.4 3.9 1.0 2.72.4 Mo0.1/i0.6 alloy Ni-base — 10.0 2.0 1.0 2.5 Bal Si5.4 alloy Fe-base— 25.0 — 1.0 Bal 4.0 Mo2.0 alloy Insert — — — — — Bal Si0.6/B3.0material

[0104] During the liquid phase diffusion welding, though the insertmaterial melts, Co-base alloy 48, the valve 42 and the valve seat 47 donot melt. The Co-base alloy 48 after the joining maintains the metalstructure where multiple grains or clusters of eutectic carbide aredistributed discontinuously in the base material.

[0105] After the welding, the eutectic carbide still exists as grains orclusters on the surface or the inside of the Co-base alloy 48. Theexistence of the grains or clusters of the eutectic carbide in theCo-base alloy 48 limits the exposure of the eutectic carbide, resultingin restraining the damage.

[0106] If the Co-base alloy 48 where the eutectic carbide is diffuseddiscontinuously as grains or clusters is exposed to a corrosiveenvironment of sulfur, the grains or clusters of the eutectic carbidewhich are in contact with the corrosive environment are detached fromthe surface as the result of the corrosion or the sliding action, andonly the base material without the eutectic carbide exists on thesurface which is in contact with the corrosive environment. A phenomenonwhere corrosion and detaching happen alternately and repeatedly isprevented, thereby restraining the damage.

[0107] If the coefficient of friction of the Co-base alloy 48 includingeutectic carbide composed as grains or clusters is measured at roomtemperature under high surface pressure (about 2000 kg/cm²), and isindicated as a developed material in a chart, the coefficient offriction is as low as ½ to ⅔ of that of a conventional Co-base alloyhaving mesh-like eutectic carbide as indicated in FIG. 9.

[0108] The engine valve 42 is assumed to be used at a high temperature(up to about 500 to 600° C.) and with a large number of sliding motions.The test result shows the low friction under the high surface pressure.Though the coefficient of friction is governed by the ratio of shearingstrength and degree of hardness, the ratio of searing strength anddegree of hardness of the material has little dependency on temperature,and it is assumed that no change is observed if materials have the samecomposition. Thus the effect of the low friction is gained at a hightemperature and with a large number of sliding motions.

[0109] For comparing the corrosion-resisting capability, Strauss testand an erosion test in diluted sulfuric acid were conducted. As theresult, the Co-base alloy 48 (developed material) shows acorrosion-resisting capability 30 times as much as that of the Co-basealloy including eutectic carbide composed as mesh as indicated in Table1 in the Strauss test. The Co-base alloy shows durability 20 to 30 timesas much as that of the Co-base alloy including eutectic carbide composedas mesh in the erosion test in diluted sulfuric acid.

[0110] With the present embodiment, high corrosion resistance, lowwearing and low friction achieves the durability and the reduction ofthe power loss of the valve system, thereby increasing efficiency,output and durability of the engine as a whole.

[0111] The Co-base alloy adopted for this embodiment can be the Co-basealloy including components described in Table 2, or a Ni-base alloy or aFe-base alloy which includes grain-like or cluster-like eutectic carbideand is made by hot forging from the Ni-base alloy or the Fe-base alloyhaving components indicated in Table 3 can replace the Co-base alloy 48,and increases efficiency, output and durability of the engine as awhole.

[0112] In this case, a joining mean and a joining condition for joiningthe Co-base alloy, the Ni-base alloy or the Fe-base alloy to the valve42 and the valve seat 47 are selected such that the eutectic carbideexists as grains or clusters in the Co-base alloy, the Ni-base alloy orthe Fe-base alloy after the joining. The preferable method as thejoining mean is liquid phase diffusing welding.

[0113] In the present embodiment, the Co-base alloy, the Ni-base alloyor the Fe-base alloy including grain-like or cluster-like eutecticcarbide is joined with the liquid phase diffusion welding to partshaving a seal capability on the valve 42 and the valve seat 47 of theengine, thereby providing seal faces having strength, wear-resistingcapability, corrosion-resisting capability and low friction whilemaintaining a high degree of hardness.

[0114] Preventing corrosion caused by sulfuric component and the likeincluded in gasoline as the fuel of the engine, a progress of crackstarting from the corrosion, and the decrease of the seal capabilitycaused by erosion provide a seal face with a low friction to prevent thedecrease of the engine efficiency caused by friction, therebycontributing the increase of the engine output in addition to increasingthe durability of an internal combustion engine, and preventing thedecrease of the engine efficiency.

[0115] Using the liquid phase diffusion welding to join the Co-basealloy, the Ni-base alloy or the Fe-base alloy including grain-like orcluster-like eutectic carbide from Table 2 and Table 3 to an externalperipheral surface of the valve lifter 44 constituting the valve systemof the engine increases the durability of the engine, and prevents thedecrease of the engine efficiency further.

[0116] If the Co-base alloy including the mesh-like eutectic carbide isdesignated as a conventional example, and the Co-base alloy includingcomponents shown in Table 2 diffused discontinuously as grains orclusters is designated as the present embodiment, the comparison betweenthe both alloys shows the differences in capability as in Table 4. TABLE4 Evaluated item Conventional example Present embodiment Tensilestrength N/mm² 920 1064 Compressive stress N/mm² 1700 More than 1700Impact value kgm/cm² 0.2  8 to 10 Coefficient of friction 0.4 0.16 to0.19 Hardness (HRC) 43 43 to 45 SOx corrosion sensitivity Yes No

[0117] Since the alloys from the conventional example and the presentinvention present differences in the capability as described before, ifthe valve lifter is used after the alloy from the present invention isattached with the liquid phase diffusion welding, the engine output losscaused by the friction in the valve system is reduced. If the valve andthe seat are used after the alloy from the present invention is attachedwith the liquid phase diffusion welding, they do not presentcorrosion'sensitivity under SOx atmosphere and a high impact value,thereby maintaining the health of the valve and the seat.

[0118] The corrosion-resisting and wear-resisting alloy of the presentinvention is also applied to a pump facility as described below. In apump facility shown in FIG. 16, an electric motor or the like rotates ashaft 50, and an impeller 51 fixed to the shaft 50 rotates in a pumpcasing 52. The rotation of the impeller 51 increase the pressure ofliquid X which flows into the pump casing 52, and the liquid X isdischarged outward from the pump casing 52.

[0119] A mechanical seal is adopted between the liquid X and gas Y toprevent the liquid X from leaking into the gas Y side. The mechanicalseal is shown in FIG. 17. The mechanical seal in FIG. 17 is providedwith the following constitution.

[0120] A fastener 55 is placed in a periphery of the shaft 50 inside aseal box 53 integrated with the pump casing 52. The fastener 55 is fixedto the shaft 50 with a knock 54. In side the fastener 55, a spring 56, apressing member 57, a packing 58, and a washer 59 are provided aroundthe shaft 50.

[0121] A seal cover 60 provided in the periphery of the shaft 50 isattached to an end of the seal box 53. A seat 61 provided in theperiphery of the shaft 50 is attached to the seal cover 60.

[0122] Since the spring 56 presses the pressing member 57, the packing58, and the washer 59 toward the right direction, a washer 59 is pressedagainst the seat 61 at a sealed end face S. Pressing the washer 59 tothe seat 61 with the spring 56 seals the liquid X to prevent it fromleaking to the gas Y side.

[0123] The fastener 55, the spring 56, the pressing member 57, thepacking 58, and the washer 59 rotate with the shaft 50, and the seat 61does not rotate. Heat is generated at the sealed end face S, therebyaccelerating seizure, wear, and corrosion at the sealed end face S.Thus, a mechanical seal using a wear-resisting and corrosion-resistingmaterial is needed at the sealed end face.

[0124] To satisfy the requirement, in the present embodiment, a plate 62made of a corrosion-resisting and wear-resisting alloy is attached to apart where the washer 59 comes in contact with the seat 61 as indicatedFIG. 17. Either of the alloys described before is applied as thecorrosion-resisting and wear-resisting alloy, and the eutectic carbideis distributed discontinuously as grains or clusters in the base of thealloy. The alloy is joined to the washer 59 with liquid phase diffusingwelding. The joining method and the joining condition for the liquidphase diffusion welding are the same as those described before. Asimilar corrosion-resisting and wear-resisting alloy may be attached toa part where the seat 61 comes in contact with the washer 59. Thecorrosion-resisting and wear-resisting alloy may be attached both to thewasher 59 and the seat 61 where they come into contact with each otherto make the corrosion-resisting and wear-resisting alloy on the bothparts come in contact with at the sealed end face S.

[0125] With this embodiment, since the corrosion-resisting andwear-resisting alloy joined to at least either of the washer 59 or theseat 61 includes the grain-like or cluster-like eutectic carbidediffused as a discontinuous distribution, it is maintained such that ithardly develops corrosion, and the coefficient of friction is maintainedas low as that of the corrosion-resisting and wear-resisting alloy inFIG. 9.

[0126] Increased corrosion resisting capability and decreased frictionat the sealed end face S are achieved under a corrosive environmentincluding sulfuric component or dissolved oxygen. With the presentembodiment, the capability of the mechanical seal is maintained for along period, thereby providing a mechanical seal with high reliability.Since the capability of the mechanical seal is maintained for a longperiod, the reliability of a pump using the mechanical seal and thereliability of a plant using the pump increase.

[0127] Conventionally the washer 59 is used after a Co-base alloy isoverlaid on the sealed end face S of the washer 59, and the seat 61 ismade of carbon impregnated with burnt phenol, carbon formed with phenol,or carbon impregnated with white. The capability of thecorrosion-resisting and wear-resisting alloy (Co-base alloy) used foreither the washer 59 or the seat 61 or the both of the washer 59 and theseat 61 in the present embodiment where the grain-like or cluster-likeeutectic carbide is distributed discontinuously in the base material iscompared with that of the conventional example in Table 5. The Co-basealloy in the present embodiment in Table 5 has the components describedin Table 2, and the grain-like or cluster-like eutectic carbide arediffused discontinuously in the alloy. TABLE 5 Conventional example SeatEmbodiment Carbon Carbon of the impreg- Carbon impreg- present inventionnated with formed nated Washer Seat Washer burnt with with Co-baseCo-base Item Overlay phenol phenol white alloy alloy Tensile 920 2.5 3to 3.5 — 1064 1064 strength N/mm² Compressive 1700 8 17 to 14 More Morestress 17.5 than than N/mm² 1700 1700 Impact value 0.2 — 2 to 3 — 8 to10 8 to 10 kgm/cm² Coefficient 0.4 — 0.25 — 0.16 to 0.16 to of friction0.19 0.19 Hardness 43 46 37 to 53 46 43 to 43 to (HRC) 45 45Withstanding More — 180 200 More More temperature than than than (° C.)300 300 300

[0128] With these differences in the capability, the mechanical seal inthe present embodiment restrains seizure, wear and corrosion at thesealed end face S. The present embodiment provides a mechanical sealwhich withstands a compressive stress and an impact value higher thanthe conventional ones.

[0129] After the plate 62 made of the corrosion-resisting andwear-resisting alloy is joined to a washer 59 or the like, thegrain-like or cluster-like eutectic carbide exists discontinuously inthe base material of the corrosion-resisting and wear-resisting alloy,thereby providing a high corrosion-resisting capability and restraininga leak at the sealed end face S, resulting in preventing erosion at thesealed end face S caused by the leak. The present embodiment provides amechanical seal with a high capability.

[0130] During the operation of the pump facility indicated in FIG. 16,the washer 59 rotates with the rotating shaft 50, and a plate 62attached to the washer 59 rotates while the plate 62 is in contact withthe stationary seat 61 fixed to the pump casing 52. The contact betweenthe plate 62 and the seat 61 provides a seal between the rotating shaft50, which is a member of the rotating side, and the pump casing 52,which is a member of the stationary side, thereby preventing a leak ofliquid. A mechanical seal device in the pump facility comprises thewasher 59, the plate 62 and the seat 61. A first seal comprises thewasher 59 (main body side) and the plate 62 (the corrosion-resisting andwear-resisting alloy). A second seal comprises the seat 61. The firstseal may be provided on the pump casing 52. The second seal may beprovided on the rotating shaft 50 side. The second seal provided on thepump casing 52 may be constituted in the same way as that of the firstseal.

[0131] The plate 62 rotates at a high speed while it is always incontact with the seat 61 with an action of the spring 56 to maintain thesealing capability. Though wear, seizure, and corrosion of the plate 62forming the seal face are suspected, the plate is excellent in thewear-resisting capability and corrosion-resisting capability since theeutectic carbide is formed as grains or clusters as described before,thereby presenting little wear. The plate 62 is also excellent incorrosion-resisting capability, thereby preventing a corrosion caused bya contact with liquid. This decreases the frequency of maintaining themechanical seal device, thereby extending the life of the mechanicalseal device. This leads to a reduction of maintenance operation of thepump facility. Since the plate 62 constituted with thecorrosion-resisting and wear-resisting alloy including grain-like orcluster-like eutectic carbide has coefficient of friction as small asabout 0.16, the ratio at which rotating power of the rotating shaft 50changes into heat energy at the contact part between the plate 62 andthe seat 61 is extremely small. The loss of the rotating power of therotating shaft 50 is small.

[0132] The mechanical seal device including a corrosion-resisting andwear-resisting alloy having grain-like or cluster like eutectic carbidesuch as the plate 62 of the present embodiment is applied to acompressor pressurizing gas and a blower requiring a seal between arotating shaft and a casing in addition to the pump of the presentembodiment, which is a fluid pressurizing device. The compressor and theblower are types of the fluid pressurizing devices. The mechanical sealdevice is also applied to a turbine where steam flows. The mechanicalseal device including a corrosion-resisting and wear-resisting alloyhaving grain-like or cluster like eutectic carbide, which is applied tothe pump facility is applied as a mechanical seal device sealing betweena rotating shaft and a casing of the turbine. The pump facility, thecompressor, the blower, and the turbine are rotating devices insidewhich fluid flows.

[0133] A preferable concept of the present invention including the pumpfacility shown in FIG. 16, the compressor, the blower and the turbine isalso recognized as in claim 15.

[0134] A preferable concept of the present invention including the pumpfacility shown in FIG. 16, the compressor, and the blower is alsorecognized as in claim 16. It is also preferable to coincide the conceptwith the concepts described in claim 17 or claim 20.

What is claimed is:
 1. A corrosion-resisting and wear-resisting alloy,which is obtained by selecting a material from cobalt base added with Crand/or W, nickel base added with Fe and/or Cr, and iron base added withCr and/or Ni, casting said material into an ingot or a slab as anintermediate material, applying hot plastic forming at a temperaturewhich is 650° C. or more and the solidus temperature or less to saidintermediate material, which includes a structure comprising mesh-likeeutectic carbide and a base material surrounded by the eutectic carbide,forming the eutectic carbide as a discontinuous distribution in a formof multiple grains or clusters, wherein the coefficient of friction is0.1 to 0.5, and the Vickers hardness without age hardening process is300 to 600 Hv.
 2. A corrosion-resisting and wear-resisting alloyaccording to claim 1, wherein the coefficient of friction is 0.3 orless.
 3. A corrosion-resisting and wear-resisting alloy according toclaim 1, wherein the cobalt base added with Cr and/or W comprises 0.1 to3.5% of C, 25% or less of Ni, 25 to 35% of Cr, 5% or less of Fe, 20% orless of W, 1.5% or less of Mo, and 1.5% or less of Si in weight ratio,the balance Co and inevitable impurities.
 4. A corrosion-resisting andwear-resisting alloy according to claim 1, wherein the nickel base addedwith Fe and/or Cr comprises 0.1 to 2.5% of C, 3 to 9% of Si, 7 to 25% ofCr, 0.5 to 5% of B, 2 to 6% of Fe, 1 to 5% of W, and 17% or less of Moin weight ratio, the balance Ni and inevitable impurities.
 5. Acorrosion-resisting and wear-resisting alloy according to claim 1,wherein the iron base added with. Cr and/or Ni comprises 0.1 to 1.5% ofC, 0.3 to 4% of Si, 4 to 9% of Ni, 3% or less of Mo, 6 to 10% of Mn, and15 to 25% of Cr in weight ratio, the balance Fe and inevitableimpurities.
 6. A fluid device wherein the corrosion-resisting andwear-resisting alloy according to claim 1 is used for a wear-resistingpart or an erosion shield part.
 7. A fluid device wherein thecorrosion-resisting and wear-resisting alloy according to claim 1 withthe coefficient of friction of 0.1 to 0.3 is used for a wear-resistingpart or an erosion shield part.
 8. A dynamic device wherein thecorrosion-resisting and wear-resisting alloy according to claim 1 isjoined with a base metal without changing the metal composition forapplication to a sliding part or a contact part.
 9. A dynamic devicewherein the corrosion-resisting and wear-resisting alloy according toclaim 1 with the coefficient of friction of 0.1 to 0.3 is joined with abase metal without changing the metal composition for application to asliding part or a contact part.
 10. A valve, which is provided with avalve element and a valve casing, wherein valve seats are provided oncontact faces of both of the valve element and the valve casing, and abase body of said valve seats is provided with a member which comprisesone type of alloy selected from a cobalt-base alloy, a nickel-basealloy, and an iron-base alloy, in which grain-like or cluster-likeeutectic carbide is diffused as a discontinued distribution, and whichhas the coefficient of friction of 0.1 to 0.3.
 11. A nuclear powerplant, which is provided with a piping system including a valve on apiping through which a coolant flows, wherein said valve is a valveaccording to claim
 10. 12. A pump wherein a seat and a washer, whichrelatively rotate about a rotating shaft of the pump, are in contactwith each other at a sealed end, and either of the contact faces of thesaid seat or said washer is provided with a member which comprises onetype of alloy selected from a cobalt-base alloy, a nickel-base alloy,and an iron-base alloy, in which grain-like or cluster-like eutecticcarbide is diffused as a discontinued distribution, and which has thecoefficient of friction of 0.1 to 0.3.
 13. An internal combustionengine, wherein a valve seat part and a valve are provided on a cylinderhead of said internal combustion engine, valve seats are respectivelyprovided on contact faces of both of said valve seat part and saidvalve, and surfaces of base bodies of said valve seats is provided witha member which comprises one type of alloy selected from a cobalt-basealloy, a nickel-base alloy, and an iron-base alloy, in which grain-likeor cluster-like eutectic carbide is diffused as a discontinueddistribution, and which has the coefficient of friction of 0.1 to 0.3.14. An internal combustion engine, wherein at least either of contactfaces of a valve lifter or a cam of the internal combustion engine isprovided with a member which comprises one type of alloy selected from acobalt-base alloy, a nickel-base alloy, and an iron-base alloy, in whichgrain-like or cluster-like eutectic carbide is diffused as adiscontinued distribution, and which has the coefficient of friction of0.1 to 0.3.
 15. A rotating device comprising: a casing in which liquidflows; a rotating shaft which is inserted into said casing; and amechanical seal device which seals between said rotating shaft and saidcasing; wherein said mechanical seal device is provided with a firstseal, which rotates with said rotating shaft, and a second seal, whichis provided on said casing and is in contact with said first seal, atleast either of said first seal or said second seal includes acorrosion-resisting and wear-resisting alloy where grain-like orcluster-like eutectic carbide is diffused in a matrix part of a metalmicro structure, and which is in contact with the other seal, and a mainbody, and said corrosion-resisting and wear-resisting alloy isdiffusion-welded to said main body.
 16. A liquid pressurizing devicecomprising: a casing; a rotating shaft inserted into said casing; afluid pressurizing mean which is provided on said rotating shaft andpressurizes fluid; and a mechanical seal device which seals between saidrotating shaft and said casing; wherein said mechanical seal device isprovided with a first seal, which rotates with said rotating shaft, anda second seal, which is provided on said casing and is in contact withsaid first seal, at least either of said first seal or said second sealincludes a corrosion-resisting and wear-resisting alloy where grain-likeor cluster-like eutectic carbide is diffused in a matrix part of a metalmicro structure, and which is in contact with the other seal, and a mainbody, and said corrosion-resisting and wear-resisting alloy isdiffusion-welded to said main body.
 17. A liquid pressurizing deviceaccording to claim 16 wherein said corrosion-resisting andwear-resisting alloy has 0.1 to 0.3 of coefficient of friction, and 300to 600 Hv of Vickers hardness without age hardening process.
 18. Aliquid pressurizing device according to claim 17 wherein saidcorrosion-resisting and wear-resisting alloy is constituted with acobalt base material added with Cr and/or W comprises 0.1 to 3.5% of C,25% or less of Ni, 25 to 35% of Cr, 5% or less of Fe, 20% or less of W,1.5% or less of Mo, and 1.5% or less of Si in weight ratio, the balanceCo and inevitable impurities.
 19. A liquid pressurizing device accordingto claim 17 wherein said corrosion-resisting and wear-resisting alloy isconstituted with a nickel base material added with Fe and/or Crcomprises 0.1 to 2.5% of C, 3 to 9% of Si, 7 to 25% of Cr, 0.5 to 5% ofB, 2 to 6% of Fe, 1 to 5% of W, and 17% or less of Mo in weight ratio,the balance Ni and inevitable impurities.
 20. A liquid pressurizingdevice according to claim 17 wherein said corrosion-resisting andwear-resisting alloy is constituted with an iron base material addedwith Cr and/or Ni comprises 0.1 to 1.5% of C, 0.3 to 4% of Si, 4 to 9%of Ni, 3% or less of Mo, 6 to 10% of Mn, and 15 to 25% of Cr in weightratio, the balance Fe and inevitable impurities.